JP2005048733A - Co-generation system with exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a co-generation system and exhaust emission control method, having high energy efficiency and removing nitrogen oxide in purifying exhaust gas discharged from a reciprocating engine of the co-generation system. <P>SOLUTION: The co-generation system includes an exhaust emission control device for purifying the exhaust gas from the reciprocating engine 1. The exhaust emission control device is so constructed that an oxidation unit 2 containing an oxidation catalyst, a recovery unit 3 containing an exhaust heat recovery device and a denitration unit 4 containing a denitration catalyst are disposed in order directing from the upstream side of exhaust gas discharged from the engine 1 toward the downstream side. In this device, in purifying the exhaust gas, the exhaust gas is brought into contact with the oxidation catalyst at about 350 to 600°C to remove hydrocarbon (especially non-methane hydrocarbon), and then heat energy is recovered from the exhaust gas by the exhaust heat recovery device. Further, in the presence of ammonium, the exhaust gas is brought into contact with the denitration catalyst at about 180 to 350°C to remove the nitrogen oxide. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention uses a reciprocating type (piston type) engine such as a gas engine or a diesel engine, and also includes a combined heat and power supply apparatus equipped with an exhaust gas purification device for purifying exhaust gas discharged from these engines, and exhaust gas purification. Regarding the method.

  A combined heat and power device is a device that drives a prime mover (engine) using fuel to generate power, and recovers thermal energy of exhaust gas discharged from the engine as steam or hot water using a waste heat boiler or the like. In recent years, its use has greatly expanded in order to contribute to effective use. Since such a combined heat and power supply device is often used in a relatively densely populated area due to its characteristics, it is often operated with exhaust gas purification measures such as removal of nitrogen oxides.

  For the purification of nitrogen oxides, an ammonia selective reduction method is used in which a catalyst composed of titanium oxide is supported on a catalyst that supports vanadium oxide or the like as an active component, and nitrogen oxide is reduced to nitrogen using ammonia as a reducing agent. The Furthermore, recently, instead of ammonia, a method using urea water that is easy to handle has become widespread, and its application range has expanded.

  On the other hand, in addition to nitrogen oxides, the engine exhaust gas contains a small amount of hydrocarbons, carbon monoxide, sulfur oxides, VOC (volatile organic compounds), PM (particulate matter), and the like. Among them, in recent years, VOC has attracted attention as an odor-causing substance. In particular, in the VOC component in exhaust gas, oxygen-containing compounds such as aldehydes and carboxylic acids have a low acceptable threshold and are the main cause of odor. Since these substances are decomposed into carbon dioxide and water by oxidation, they are generally easier to remove than hydrocarbons. For example, as disclosed in JP-A-9-285720 (Patent Document 1) and JP-A-10-309443 (Patent Document 2), an oxidation catalyst in which platinum is supported on alumina or zeolite is used. Thus, these substances can be removed.

  As a method of using a catalyst for removing nitrogen oxides and an oxidation catalyst in combination, for example, Japanese Patent Publication No. 5-16886 (Patent Document 3) includes exhaust gas such as gasoline and diesel engine in an oxidizing atmosphere, A method for purifying exhaust gas in which an acid metal oxide such as titanium oxide is brought into contact with an oxidation catalyst in the presence of hydrocarbon is disclosed. This method can remove unreacted excess hydrocarbon in the reduction reaction of nitrogen oxides using hydrocarbon as a reducing agent. Japanese Patent Laid-Open No. 5-38420 (Patent Document 4) discloses that nitrogen oxides in exhaust gas such as gasoline and diesel engines are converted into nitrogen dioxide through an oxidation catalyst in advance, and then the presence of hydrocarbons in an oxidizing atmosphere. Below, a method for removing nitrogen oxides in contact with an acidic metal oxide such as titanium oxide is disclosed. In this document, at the reaction temperature of 100 to 800 ° C., the step of contacting the first stage oxidation catalyst and the step of contacting the second stage reduction catalyst are continuously processed.

  However, these methods are all methods related to the reduction reaction of nitrogen oxides using hydrocarbon as a reducing agent, and are not reduction reactions of nitrogen oxides using ammonia as a reducing agent. Further, these methods do not sufficiently remove odor components.

  Japanese Patent Laid-Open No. 11-226360 (Patent Document 5) discloses a method for decomposing nitrogen oxides in exhaust gas using ammonia as a reducing agent. A method using an oxidation catalyst containing the above is disclosed. In this method, an oxidation catalyst is used to reduce ammonia (leak ammonia) remaining in the exhaust gas after treatment. Japanese Patent Laid-Open No. 2000-303826 (Patent Document 6) is an apparatus for purifying exhaust gas from a diesel engine using a denitration catalyst, and an oxidation catalyst and a filter are provided upstream of the denitration catalyst in the exhaust passage. An exhaust gas purification device is disclosed. In this apparatus, the oxidation catalyst and the filter are combined to suppress poisoning of the denitration catalyst due to sulfur contained in the exhaust gas.

However, even if these methods and apparatuses are used, it is not possible to reduce odor components contained in the exhaust gas of a reciprocating engine, particularly VOCs such as oxygen-containing organic compounds.
JP-A-9-285720 (Claims, paragraph number [0013]) JP-A-10-309443 (Claims, paragraph number [0016]) Japanese Patent Publication No. 5-16886 (Claims, column 5, lines 18-25, column 6, lines 22-31, column 7, lines 18-23) Japanese Patent Laid-Open No. 5-38420 (claims, paragraph numbers [0016] [0017] [0023]) JP 11-226360 A (Claim 1, paragraph numbers [0008] [0020]) JP 2000-303826 (Claim 1, paragraph numbers [0011] [0015] [0018])

  Accordingly, it is an object of the present invention to provide a combined heat and power supply apparatus and an exhaust gas purification method that can remove nitrogen oxides with high energy efficiency in purification of exhaust gas discharged from a reciprocating engine of the combined heat and power supply apparatus. .

  Another object of the present invention is to provide a combined heat and power device and a method for purifying exhaust gas that can remove odorous substances such as VOC components in purification of exhaust gas discharged from a reciprocating engine of the combined heat and power device.

  As a result of studying the application of an oxidation catalyst and a denitration catalyst together to an actual engine exhaust gas, the present inventors have unexpectedly found that when these oxidation catalyst and denitration catalyst are used in combination, It has been found that the removal performance is not greatly affected, but the VOC component may increase rather than decrease. Further investigations have shown the possibility that VOC components are produced from hydrocarbons contained in engine exhaust gas on the oxidation catalyst and / or denitration catalyst.

  And, as a result of intensive investigations to solve the above problems based on these findings, the inventors of the present invention, as a result, in the exhaust gas purification apparatus of a combined heat and power unit having a reciprocating engine, the exhaust gas from the upstream side to the downstream side It was found that the energy efficiency is high and nitrogen oxides can be removed by arranging an oxidation unit including an oxidation catalyst, a recovery unit including an exhaust heat recovery device, and a denitration unit including a denitration catalyst in this order.

  That is, the combined heat and power device of the present invention is a combined heat and power device provided with an exhaust gas purification device for purifying exhaust gas from a reciprocating engine, and the exhaust gas purification device is upstream of the exhaust gas discharged from the engine. From the side toward the downstream side, an oxidation unit including an oxidation catalyst, a recovery unit including an exhaust heat recovery device, and a denitration unit including a denitration catalyst are arranged in this order. The oxidation catalyst may be a catalyst in which a noble metal element is supported on a refractory inorganic carrier.

  The present invention is a method for purifying exhaust gas discharged from a reciprocating engine of a combined heat and power supply device, after contacting the exhaust gas with an oxidation catalyst, recovering thermal energy of the exhaust gas by an exhaust heat recovery device, Further, a method for purifying exhaust gas in which exhaust gas from which thermal energy has been recovered is brought into contact with a denitration catalyst is also included. In this method, ammonia or a compound that generates ammonia may be added in contact with the denitration catalyst. In the method, the hydrocarbon may be a non-methane hydrocarbon. Moreover, in the said method, waste gas may be made to contact with an oxidation catalyst at about 350-600 degreeC, and may be made to contact with a denitration catalyst at about 180-350 degreeC.

  Further, in the present invention, exhaust gas discharged from the reciprocating engine of the combined heat and power unit is circulated in the order of an oxidation unit including an oxidation catalyst, a recovery unit including an exhaust heat recovery device, and a denitration unit including a denitration catalyst. A method for removing odorous substances and nitrogen oxides from the exhaust gas is also included.

  In the present invention, in purification of exhaust gas discharged from a reciprocating engine of a combined heat and power supply device, energy efficiency is high (without impairing economy) and nitrogen oxides can be removed. Furthermore, odorous substances such as VOC components can be efficiently removed.

  The combined heat and power device of the present invention includes a reciprocating engine and an exhaust gas purification device.

  Examples of the reciprocating engine include a gas engine, a diesel engine, and a gasoline engine. The type of engine is not particularly limited, but it is effective to use an engine that exhausts exhaust gas having a hydrocarbon concentration in exhaust gas of, for example, 100 ppm or more in terms of total hydrocarbons (THC). Further, from the viewpoint of effectively reducing the odor component in the exhaust gas, the hydrocarbon concentration in the exhaust gas of the engine is, for example, about 100 to 10,000 ppm, preferably 300 to 5000 ppm, more preferably about 500 to 3000 ppm in terms of THC. is there.

  The exhaust gas purifying apparatus includes an oxidation unit including an oxidation catalyst, a recovery unit including an exhaust heat recovery apparatus, and a denitration unit including a denitration catalyst.

  The oxidation catalyst contained in the oxidation unit is an oxidation catalyst in which an active metal such as a noble metal element is supported on a refractory inorganic carrier.

  Examples of the refractory inorganic carrier include periodic table group 3A metal oxides such as ceria, periodic table group 3B metal oxides such as alumina, periodic table group 4 metal oxides such as titania and zirconia, and silica. Examples include periodic group 4B metal oxides and composite metal oxides such as zeolite, silica alumina, silica zirconia, and alumina titanium. These inorganic carriers can be used alone or in combination of two or more. Among these, ceria, titania, zirconia, alumina, silica and the like are usually used, and periodic table group 4 metal oxides such as zirconia are preferable.

  Examples of noble metal elements include Group 8 metal elements of the periodic table such as ruthenium, rhodium, iridium, palladium, platinum, and Group 1B metal elements of the periodic table such as silver and gold. These noble metal elements can be used alone or in combination of two or more. Of these noble metal elements, Group 8 metal elements of the periodic table, particularly rhodium, iridium, palladium and platinum are preferred.

  The amount of the active metal supported is, for example, about 0.1 to 50 parts by weight, preferably about 0.3 to 30 parts by weight, and more preferably about 0.5 to 10 parts by weight with respect to 100 parts by weight of the inorganic carrier. The amount of the active metal supported may be, for example, about 0.5 to 20 g per liter of the inorganic carrier in terms of the volume of the inorganic carrier.

  The oxidation catalyst can be produced by a conventional method. For example, by adding a powdery inorganic carrier to an aqueous solution containing an active metal compound (nitrate, acetate, complex salt, etc.) and stirring, After impregnating with a noble metal compound, it can be produced by an impregnation method of drying and baking.

  The shape of the oxidation catalyst is not particularly limited and may be, for example, a granular shape, a plate shape, or a rod shape. However, from the viewpoint of contact efficiency with exhaust gas, a honeycomb shape or a fiber shape, particularly a honeycomb shape is preferable. Examples of the method for making the shape of the oxidation catalyst into a honeycomb include a method of coating an oxidation catalyst on a honeycomb-shaped support (such as a ceramic body) and a method of forming into a honeycomb using a binder component.

  The exhaust heat recovery device included in the recovery unit is not particularly limited as long as it is a device that recovers the thermal energy possessed by the exhaust gas with a heat medium (liquid or gas such as water, silicone oil, mineral oil) and uses it as a heat source. As the exhaust heat recovery device, usually, an exhaust heat recovery device such as an exhaust heat boiler using water as a heat medium can be used. The exhaust heat recovery apparatus includes a pipe capable of circulating a heat medium and a supply unit capable of supplying exhaust gas around the pipe, and can recover thermal energy through heat exchange through the pipe.

  As a denitration catalyst contained in the denitration unit, a conventional denitration catalyst, for example, titanium oxide as a main component, vanadium oxide, and tungsten oxide, iron oxide, copper oxide, manganese oxide, chromium oxide, molybdenum oxide as necessary. A denitration catalyst containing a metal oxide such as can be used. The crystal form of titanium oxide may be a rutile type, but is usually anatase type. The denitration catalyst may contain an auxiliary for molding (such as inorganic fibers).

  The proportion of vanadium oxide is, for example, 1 to 50 parts by weight, preferably 3 to 30 parts by weight, and more preferably about 5 to 20 parts by weight with respect to 100 parts by weight of titanium oxide.

  The ratio of the other metal oxide is, for example, 0 to 40 parts by weight, preferably 0 to 20 parts by weight, and more preferably about 0 to 10 parts by weight with respect to 100 parts by weight of titanium oxide.

  The shape of the denitration catalyst is not particularly limited, and may be, for example, granular, plate-like, or rod-like.

  The denitration catalyst is kneaded by adding a vanadate (such as ammonium vanadate), if necessary, other metal acid salt (such as ammonium tungstate), and water to a conventional method, for example, titanium oxide. It can be obtained by a method of drying and baking.

  In the combined heat and power device of the present invention, the exhaust gas purifying device is arranged in the order of an oxidation unit, a recovery unit, and a denitration unit from the upstream side to the downstream side of the exhaust gas. By arranging the units of the exhaust gas purification device in this order, the heat energy of the exhaust gas heated in contact with the oxidation catalyst can be efficiently recovered by the exhaust heat recovery device, and the exhaust gas recovery can The temperature is lowered to a temperature suitable for denitration, and nitrogen oxides can be removed efficiently. Furthermore, by removing hydrocarbons, which are precursors of odorous substances, in the previous step of the denitration catalyst, not only nitrogen oxides but also odorous substances such as VOC components can be efficiently removed. In the combined heat and power device of the present invention, the arrangement form for the exhaust gas discharged from the reciprocating engine to circulate through each unit of the exhaust gas purification apparatus may be a vertical type or a horizontal type. There may be. A method for purifying exhaust gas using such an apparatus will be described below.

In the exhaust gas purification method of the present invention, first, hydrocarbons are removed by contacting the exhaust gas with an oxidation catalyst. Examples of hydrocarbons include non-methane hydrocarbons such as C _2-6 alkanes (preferably C _2-4 alkanes) such as ethane, propane, and butane, and C _2-4 alkenes such as ethylene, propylene, and butylene. Can do. These non-methane hydrocarbons are not direct odor substances, but if they are not removed before the exhaust gas is treated with a denitration catalyst, they are changed to oxygenated compounds in the denitration process, which causes the generation of VOC components. The exhaust gas includes oxygen-containing organic compounds that are VOC components, for example, carboxylic acids such as acetic acid and butyric acid, and aldehydes such as formaldehyde and acetaldehyde.

  The temperature at which the exhaust gas and the oxidation catalyst are brought into contact is, for example, about 350 to 600 ° C, preferably about 380 to 550 ° C, and more preferably about 380 to 520 ° C (particularly 450 to 520 ° C). When oxidation treatment is performed at such a temperature, it is possible to improve the removal performance of hydrocarbons and to suppress deterioration of the oxidation catalyst (deterioration of performance over time).

In the oxidation unit, space velocity is usually per gas hourly 20,000～300,000H ^-1, is preferably 30,000～200,000H ^-1, more preferably 50,000~100,000h about ^-1 . The amount of the oxidation catalyst used is such that the removal rate of non-methane hydrocarbons is, for example, 50% or more (for example, 50 to 99.99%), preferably 70% or more (for example, 70 to 99). 0.9%), more preferably 80% or more (for example, 80 to 99.5%). The larger the amount of catalyst and the amount of active metal supported, the better the performance, but it is economically disadvantageous.

  Next, the thermal energy of the exhaust gas from which hydrocarbons have been removed by the oxidation catalyst is recovered by the exhaust heat recovery device and reduced to a temperature suitable for denitration by the denitration catalyst. In the present invention, by utilizing the difference between the oxidation temperature by the oxidation catalyst and the denitration temperature by the denitration catalyst, it becomes possible to remove nitrogen oxides and odorous substances with high energy efficiency as the entire apparatus. In the exhaust heat recovery device, for example, 50 ° C. or higher (for example, 50 to 500 ° C.), preferably 100 ° C. or higher (for example, 100 to 400 ° C.), more preferably 150 ° C. or higher (for example, 150 to 300 ° C.). Thermal energy can be recovered from the exhaust gas.

  The exhaust gas from which the heat energy has been recovered by the exhaust heat recovery device comes into contact with the denitration catalyst, whereby nitrogen oxides are removed. Nitrogen oxide includes nitrogen monoxide and nitrogen dioxide, both of which are decomposed and removed by a denitration catalyst.

  In contact with the denitration catalyst, it is preferable to add ammonia or a compound that generates ammonia as a reducing agent for nitrogen oxides in the exhaust gas. Ammonia or an ammonia-generating compound is decomposed by reducing nitrogen oxides in cooperation with a denitration catalyst. The ammonia-generating compound is not particularly limited as long as it is a compound that decomposes in exhaust gas to generate ammonia, and, for example, an aqueous urea solution can be used.

  The amount of ammonia or the ammonia-producing compound added can be appropriately set according to the nitrogen oxide concentration in the exhaust gas. The amount of ammonia or the ammonia-generating compound added is, for example, 0.5 to 1.2, preferably 0.6 to 1. in terms of ammonia in volume ratio with respect to the amount of nitrogen oxide in the exhaust gas. 1, more preferably about 0.8 to 1. Ammonia or an ammonia-generating compound is usually added before contact with the denitration catalyst.

  The contact temperature between the exhaust gas (such as exhaust gas containing ammonia or an ammonia-generating compound) and the denitration catalyst is, for example, 180 to 350 ° C, preferably 200 to 320 ° C, more preferably 220 to 300 ° C (particularly 220 to 260 ° C). Degree. When the treatment is performed at such a temperature, the denitration efficiency is high and the activity of the denitration catalyst is easily exhibited sufficiently. Furthermore, when ammonia or an ammonia generating compound is added, oxidation of ammonia by oxygen is suppressed.

In the denitration unit, space velocity is usually per gas hourly 5,000～60,000H ^-1, is preferably 10,000～50,000H ^-1, more preferably 20,000~40,000h about ^-1 .

  Since the combined heat and power device of the present invention can efficiently remove not only nitrogen oxides but also odorous substances, the generation of harmful components such as hydrocarbons often occurs, and a reciprocating engine (gas engine, This is useful for a device using a diesel engine or the like. In particular, it is useful for cogeneration systems (such as a system using a gas engine) whose construction is increasing in an artificially dense urban area with the recent increase in demand for electric power.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
Cordierite honeycomb (15 cm square x 5 cm length, 200 cells per square inch (= 6.45 cm ² )) with platinum Pt supported on zirconia (Nippon Denko Co., Ltd., trade name “N-PC”) An oxidation catalyst was prepared by coating 110 g of a specific surface area of 28 m ² / g and a supported amount of Pt: 1 wt% with respect to zirconia.

Amorphous titanium oxide (manufactured by Wako Pure Chemical Industries, (Ltd.)) 100 g, ammonium vanadate (NH ₄ VO ₃₎ 10g, ammonium paratungstate _{((NH 4) 10 W 12} O 41 · 5H 2 O) 5g, 150g of water Was added, wet-kneaded, dried, and calcined at 400 ° C. to prepare a denitration catalyst.

  The denitration catalyst was tableted and 10 ml was collected with a particle size of 1 to 2 mm and packed in a quartz reaction tube (diameter 20 mm). The oxidation catalyst was cut to a diameter of 9.5 mm and a height of 17 mm, and filled in a quartz reaction tube (diameter 10 mm). Maintain the temperature of the oxidation catalyst at 500 ° C and the temperature of the denitration catalyst at 250 ° C, and distribute the gas (untreated gas) having the composition shown in Table 1 at a flow rate of 2 liters per minute (volume at 0 ° C, 1 atm). did. Nitrogen gas containing 2% ammonia was added between the oxidation catalyst and the denitration catalyst at a flow rate of 15 ml per minute (volume at 0 ° C. and 1 atm). As shown in FIG. 1, after the exhaust gas that has passed through the engine 1 comes into contact with the oxidation catalyst included in the oxidation unit 2 and the thermal energy is recovered by the exhaust heat boiler included in the recovery unit 3, the denitration unit 4 corresponds to a combined heat and power supply apparatus having an exhaust gas purifying apparatus that circulates in the order of contact with the denitration catalyst included in 4.

  The composition of the denitration catalyst outlet gas was as shown in Table 1. Here, the nitrogen oxide is the sum of nitrogen monoxide and nitrogen dioxide. It can be seen that the aldehyde and carboxylic acid, which have a low threshold and tend to cause odors, can be almost removed.

Comparative Example 1
The test was performed in the same manner as in Example 1 except that the oxidation catalyst was not used. As shown in FIG. 2, the exhaust gas that has passed through the engine 1 is circulated in the order of contact with the denitration catalyst contained in the denitration unit 4 after the thermal energy is collected by the exhaust heat boiler contained in the collection unit 3. This corresponds to a combined heat and power device having an exhaust gas purification device.

  The composition of the denitration catalyst outlet gas was as shown in Table 1. Although the aldehyde was almost removed, the carboxylic acid increased from the inlet concentration.

Comparative Example 2
The test was performed in the same manner as in Example 1 except that the temperature of the oxidation catalyst was 250 ° C. As shown in FIG. 3, after the exhaust gas that has passed through the engine 1 is recovered by the exhaust heat boiler included in the recovery unit 3 and comes into contact with the oxidation catalyst included in the oxidation unit 2, it is included in the denitration unit 4. It corresponds to a combined heat and power supply device having an exhaust gas purification device that circulates in the order of contact with the denitration catalyst.

  The composition of the denitration catalyst outlet gas was as shown in Table 1. Aldehyde can be almost removed, but carboxylic acid cannot be removed.

Comparative Example 3
The test was performed in the same manner as in Comparative Example 1 except that the gas having the composition shown in Table 2 was used instead of the gas having the composition shown in Table 1. The composition of the denitration catalyst outlet gas was as shown in Table 2. Aldehyde was almost removed and carboxylic acid was also considerably reduced, showing a result in contrast to Comparative Example 1. This result shows that carboxylic acid is produced from hydrocarbon.

  From the above results, it is understood that when exhaust gas containing hydrocarbons such as engine exhaust gas is passed through the denitration catalyst, not only the VOC component cannot be reduced but also increased. On the other hand, in the method of the present invention, the non-methane hydrocarbon is sufficiently removed in advance, so that the VOC component in the exhaust gas can be effectively reduced.

FIG. 1 is a schematic view showing a treatment flow of exhaust gas in the combined heat and power supply apparatus of the present invention used in Example 1. FIG. 2 is a schematic diagram showing a treatment flow of exhaust gas in the conventional combined heat and power supply apparatus used in Comparative Example 1. FIG. 3 is a schematic diagram showing a treatment flow of exhaust gas in the combined heat and power device used in Comparative Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Oxidation unit 3 ... Recovery unit 4 ... Denitration unit

Claims (7)

  A combined heat and power supply apparatus having an exhaust gas purification device for purifying exhaust gas from a reciprocating engine, wherein the exhaust gas purification device is an oxidation catalyst from upstream to downstream of exhaust gas discharged from the engine. The combined heat and power supply device is arranged in the order of an oxidation unit including a recovery unit including an exhaust heat recovery device and a denitration unit including a denitration catalyst.   The cogeneration apparatus according to claim 1, wherein the oxidation catalyst is a catalyst in which a noble metal element is supported on a refractory inorganic support.   A method of purifying exhaust gas discharged from a reciprocating engine of a combined heat and power supply device, contacting the exhaust gas with an oxidation catalyst, recovering thermal energy of the exhaust gas with an exhaust heat recovery device, and further recovering thermal energy Exhaust gas purification method for contacting the exhaust gas with a denitration catalyst.   The method according to claim 3, wherein ammonia or a compound that generates ammonia is added in contact with the denitration catalyst.   The process of claim 4 wherein the hydrocarbon is a non-methane hydrocarbon.   The method according to claim 4, wherein the exhaust gas is contacted with an oxidation catalyst at 350 to 600 ° C, the thermal energy of the generated exhaust gas is recovered, and the exhaust gas is contacted with a denitration catalyst at 180 to 350 ° C.   The exhaust gas discharged from the reciprocating engine of the combined heat and power unit is circulated in the order of the unit including the oxidation catalyst, the recovery unit including the exhaust heat recovery device, and the denitration unit including the denitration catalyst, and the exhaust gas odor substance and nitrogen oxidation How to remove things.

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